In modern industrial piping systems, ASME B16.5 standard, as a globally recognized technical specification for pipe flanges, is formulated by the American Society of Mechanical Engineers (ASME), and has become the preferred connecting standard in critical areas such as petrochemical, power energy, and offshore engineering, etc. ASME B16.5 weld neck flange has become the trusted piping connection safeguard by virtue of their superior structure and long service life.
ZIZI specializes in the production of various flanges of different types and materials, and the products are widely used in many industries, such as petroleum, chemical, electric power, shipbuilding, pharmaceutical, food, construction and so on.
What Is a Weld Neck Flange?
Weld Neck Flange is one of the most common types of flanges used in piping systems and is characterized by a tapered neck for direct connection to the pipeline by weld neck flanges. Designed to meet international standards such as ASME B16.5 and EN 1092-1, these flanges are the preferred connection for high pressure and high temperature service.
Core Technical Specifications of the ASME B16.5 Standard:
1. Flange Sizes
•Nominal Diameter (NPS): for flange sizes ½ inch to 24 inches (15mm to 600mm).
•Pressure Rating: 150 lbs , 300 lbs , 600 lbs , 900 lbs , 1500 lbs , 2500 lbs .
•Flange Thickness: As the pressure level increases, so does the thickness.
2. Flange Materials
•Material Selection: The standard specifies the types of materials available for flanges, such as carbon steel, alloy steel, stainless steel, aluminum alloys, etc.
•Selection basis: Work environment, stress requirements, economic costs.
3.Flange Facings
•Raised Face (RF): the sealing face is slightly higher than the flange plane, commonly used in low and medium pressure pipelines to enhance the sealing.
•Flat Face (FF): The sealing face is flush with the flange plane, suitable for low pressure or cast iron pipes.
•Ring – Type Joint (RTJ): Features a metal sealing ring for high pressure, high
4.Tolerances of Flanges
•Flange size tolerance: stipulates the permissible deviation range of each size of the flange (such as outer diameter, inner diameter, thickness, etc.) to ensure the precision of the flange in connection with the pipeline.
•Mechanical tolerance: refers to the permissible error range of various machined surfaces (such as flatness, roundness, etc.) during the manufacturing process of the flange to ensure the function and sealing performance of the flange.
ASME B16.5 Weld Neck Flange Material Selection：
| Carbon Steel | ASTM A105/A105N |
| low temperature steel | ASTM A350 LF2/LF3 |
| Pipeline steel | ASTM A694 F42/46/52/56/65/70 |
| Alloy steel | ASTM A182 F5/F9/F11/F12/F22/F91/F92 |
| Stainless steel | ASTM A182 F304/304L/304H、F316/316L、F317、F310S、F321、F347、F904L |
| Duplex stainless steel | ASTM A182 F51/53/55/60 |
Advantages of ASME B16.5 Weld Neck Flange:
•High-strength construction
•Superior sealing
•Variety of materials
•Long life design
•Global application
•Safety and reliability
Areas of Application：
•Oil & Gas
•Chemicals & Petrochemicals
•Power Industry
•Food & Pharmaceuticals
•Construction & Water Supply
•Paper & Environmental Engineering
Frequently Asked Questions (FAQs)
Why Choose ASME B16.5 Weld Neck Flange?
ASME B16.5 weld neck flanges are the preferred connection solution for high-pressure piping systems. Its unique neck design optimizes stress distribution and reduces stress concentration by more than 30%, ensuring long-term reliable operation under extreme operating conditions such as Class 2500 high pressure . The standard specifies strict material selection, manufacturing tolerances and testing requirements, and is supported by a globally recognized certification system.
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